Despite the addition of a second HD 4870, the noise level at idle of the CrossFireX system was just half a decibel higher, though the both the Southbridge and top graphics cards ran 8~9°C hotter. On load we found that the sweet spot for the fans was 9V with the system emitting 32 [email protected] At this setting, the system didn't produce any more measurable noise than 7V, but it was substantially quieter than 12V. The thermal difference between these three speeds was minor with the exception of the Southbridge. The side fan played a big part in cooling the hotter areas on the motherboard PCB.

This time around, the right side fan made a more significant contribution, lower the CPU and Southbridge temperatures by 2°C at 5V. At 12V, the fan still didn't add any noise to the system and provided a further 1°C improvement for the CPU and GPU, and a 6°C improvement for the Southbridge. It seems that the right side fan is only effective when the environment inside is hotter, as is the case with a multi-GPU system.

The acoustics of the CrossFireX system were close to that of the single HD 4870 configuration, but higher in volume, obviously. The rise from 29 [email protected] to 32 [email protected] was significant, but the noise character was similar, just higher in pitch. While it is not entirely unpleasant, headphones would be advised.

CPU fan set to 100% speed.
All temperature results adjusted to 22°C ambient.

The Dragon Rider turns the tables with the hotter CrossFireX configuration. The large left side fan gave it a huge advantage, lowering the GPU temperatures slightly and the CPU temperature by more than 10°C compared to the BUC and PC-K59. There was also a massive 17°C improvement in Southbridge temperature. The GPU fans slowed by 100~150 RPM as a result of the extra cooling, lowering the noise level a tad. For a high power, high heat system, the Dragon Rider is tough to beat.